Jenson Button is to partner Fernando Alonso at McLaren next season. The team are to announce their driver line-up at a news conference at their factory in Surrey on Thursday. But BBC Sport has learned they have decided to retain Button after weeks of leaning towards Kevin Magnussen. Button, the 34-year-old 2009 world champion, will continue into a 16th season and has his wish granted to test himself against the man widely regarded as the best in F1. McLaren signed Alonso some weeks ago, but had been vacillating over the identity of his team-mate.